Because of threats of rain last week, Aberdeen Proving Ground postponed aerial spraying for gypsy moths until today.
The spraying will be conducted from 6 to 11 a.m., and will be repeated in five to 10 days.
Residents are advised to stay indoors during the spraying, though the insecticide, called Bt, is not harmful to humans, scientists say. Cars and other automobiles should be washed after the spraying, to prevent color-spotting.
About 3,000 acres of woodland at APG will be treated to prevent the voracious moths from defoliating trees, said APG officials.